The present invention relates to a tire intended to be mounted on a rim having at least one first frustoconical seat, the generatrix of which has an axially outer end which is closer to the axis of rotation than the axially inner end.
Such a tire is described in PCT Application WO 94/13498 that is owned by the assignee of the present invention. It comprises at least a first bead, which is intended to be mounted on said first rim seat which is inclined towards the outside, said first bead, of conventional axial width, which terminates axially to the outside in a bead toe, having a bead seat, the generatrix of which has its axially outer end closer to the axis of rotation than its axially inner end, said generatrix being extended axially to the outside by an outer face defining the bead toe, said face forming with the axis of rotation an angle xcex3, which is open radially and axially towards the outside, of less than 90xc2x0. The radial carcass reinforcement of said tire, which is anchored within each bead to at least one inextensible annular reinforcement element, has a meridian profile which, when the tire is mounted on its operating rim and inflated to its operating pressure, has a direction of curvature which is constant in the sidewalls and bead which terminates in the toe, such that in said bead a line tangent to a point of tangency of said profile with the inextensible annular element of said bead forms an angle xc3x8 with the axis of rotation which is open towards the outside of at least 70xc2x0.
The bead of such a tire, and more particularly the structure of the anchoring of the carcass reinforcement, may be variable. In international application WO 95/23073 that is owned by the assignee of the present invention, the radial carcass reinforcement is anchored to the inextensible element by winding around said element from the heel to the toe of the bead to form an upturn extending into a wedge-shaped profiled element of rubber mix defined by two sides starting from an apex A located beneath the section of the coated bead wire, the radially outer side forming, with a line parallel to the axis of rotation passing through said apex A, an acute angle xc3x81, which is open radially and axially towards the outside and is between 20xc2x0 and 70xc2x0, and the radially inner side forming with said parallel line an acute angle xc3x82, which is open radially towards the inside and is between 0xc2x0 and 30xc2x0, and the rubber mix forming the profiled element, axially adjacent to the bead wire, having a Shore A hardness equal to at least 65 and greater than the Shore A hardness of the rubber mixes axially and radially above the bead wire and the profiled element.
In order to overcome the propagation towards the bead wire of cracks which begin in the outer protective layer of the bead, unpublished application PCT/EP99/10472 provides for precise location of the end of the carcass reinforcement upturn, said upturn reinforcing at least the wedge-shaped rubber profiled element which is located axially to the outside of the anchoring bead wire. Said wedge-shaped profiled element is formed of a rubber mix of greater hardness than the hardness of the rubber mixes radially above respectively the annular anchoring element and said profiled element.
Although they have solved the major problem of the propagation of cracks, the structures described above do not provide a valid solution to the initiation of said cracks, the cracks in the bead-protecting mix occur too soon in the life of the tire. Said structures furthermore have certain not insignificant drawbacks, in particular from the point of view of on the road handling crispness of passenger vehicles equipped with large tire sizes: the road holding of the vehicle under the effect of the transverse and longitudinal forces needs to be improved.
An object of the invention is to overcome the drawbacks above while preserving the excellent properties of anti-unseating of the beads of the tire from the operating rim, providing a tire which remains seated on the rim.
The tire in accordance with the invention as viewed in meridian section, comprises, a radial carcass reinforcement, two beads, each bead having a seat the generatrix of which is inclined towards the outside and a heel axially to the inside, reinforced by at least one inextensible annular element around which the carcass reinforcement is wound, extending from said heel to the toe of said bead to form an upturn, whereas the axially inner toe comprises a profiled element of rubber mix of a Shore A hardness of at least 65 and in the form of a wedge defined by three sides, two of which have originated from an apex A located beneath the annular element, the carcass reinforcement upturn being formed by the lateral and radially inner sides of said wedge-shaped profiled element and having an end located firstly axially to the outside of a straight line P2 perpendicular to the axis of rotation and passing through the center of gravity of the meridian section of the annular anchoring element and secondly axially to the inside and radially to the outside of the straight line P1 passing through said center of gravity and forming with the axis of rotation an angle open axially and radially towards the outside of between 30xc2x0 and 60xc2x0, is characterized in that at least one of the profiled elements of rubber mixes filling the space between the main part of the carcass reinforcement and its upturn and radially above the annular element and the wedge-shaped profiled element has a Shore A hardness at least equal to the hardness of the rubber mix forming said wedge-shaped profiled element, the ratio e1/e2 of the thickness e1 between the carcass reinforcement upturn and the annular anchoring element to the thickness e2 between the carcass reinforcement upturn and the outer wall of the bead, measured on the straight line P1, satisfying the relationship
0.05xe2x89xa6e1/e2xe2x89xa61.0. 
xe2x80x9cGeneratrix inclined towards the outsidexe2x80x9d is understood to mean a generatrix, the axially inner end of which lies on a circle of diameter greater than the diameter of the circle on which the axially outer end is located. xe2x80x9cDiameter of an inclined seatxe2x80x9d refers to the diameter of the circle on which is located the end of its generatrix farthest from the axis of rotation, the tire preferably has two seats which are said to be inclined towards the outside and are of different diameters.
The meridian profile of the carcass reinforcement, when the tire is mounted on its operating rim and inflated to its operating pressure, has a direction of curvature which is constant at least in the first bead and the sidewall which extends it radially, and the tangent TTxe2x80x2 to the point of tangency T of said profile with the annular reinforcement element of said bead forms with the axis of rotation an angle xc3x8 which is open towards the outside of at least 70xc2x0.